A brief overview of my MFJ 1788 loop antenna.

The antenna
Overall I have been very pleased with the purchase of the MFJ 1788 loop antenna. Considering the location I am in and the restrictions of a condo such as.....concrete all around you, other buildings blocking your signal, very small space to put an antenna and power level must be kept low as to not affect the neighbors. After doing considerable searching for the right antenna for this location it boiled down to this antenna. The power I run is 5 watts max and this is not new for me as I have been a QRP op for years now. Below are the reasons why I am pleased with this antenna to be followed by some of the not pleasing things about the antenna.
1. Very small foot print for an antenna that will give you 15m to 40m.
2. The antenna can be used mounted horizontally or vertically.
3. Once you get used to the tuning it's very fast and easy to tune.
4. I covered my antenna with as to keep it low profile and it works no problem with the cover.
5. The antenna remote control can operate either on AC or batteries.
6. Can be mounted on a simple tri-pod.

Some of the draw backs
1. The quality of the antenna is low, I had to make some adjustments to make it work as it should.
2. The band width is narrow and retuning has to be down often.
3. The SWR meter in the remote control unit is not very reliable.
4. Buzzer used to tell you the coarse tuning has finished is VERY hard to hear.
Repairing Cap spacing

On air results with this antenna have been good, with regards to receiving I have been able to hear the Middle East, South Pacific, Europe, South America and of coarse North America. Now hearing a station and contacting the station is another ball of wax. With my power restrictions I have made some very satisfying contacts. My modest signal has made it into South America, all parts of Europe, Iceland and Africa so far. There are two Loop antennas that MFJ makes and if I was to make the choice again I would had gone with the MFJ 1786 as it covers 10m to 30m. I have found with this antenna there is no way to tune it below 15m. The characteristic of the tuning capacitor will not allow it. I have read the MFJ 1788 is like a wet noodle on 40m and it's true I have not been able to make it into the U.S. The MFJ 1786 would had been a better choice with more band opportunities.   
Mike Weir, VE9KK, is a regular contributor to AmateurRadio.com and writes from New Brunswick, Canada. Contact him at [email protected].

14 Responses to “A brief overview of my MFJ 1788 loop antenna.”

  • Marc Cardinal, VA2MVC:

    Thanks so much for the review, I was hesitating between the those two models (1786, 1788) for a while now but I think it will be 1786.

  • Mike ve3wdm:

    Good morning Marc, great to read your choice has been made. Do email me and give me your impressions of the antenna once you are able to start using it.

  • David Wells KV4VE:

    Thanks for the real world review! I still have dipoles for now, but am looking at moving into an “antenna adverse” neighborhood in the near future, so am really glad to see the postings with practical experiences and opinions of alternative antennas! Keep us posted!!

  • K7ZOV Harry:

    I have the MFJ-1786 now for a few years. About 15 yrs ago I have the 1788 and liked it but had a hell of a time with it on 40 meters. The Q is extremely tight and I found hard to tune. The 1786 I have is used mostly with WSPR, PSK31 and other digital modes since it can be tuned and you don’t have to keep re-tuning with every QSO up and down the band. It is not just the MFJ product. All loop, like the popular Alex Loop or even home made ones have the same issue. You go chasing up and down the band or like band hoping you will just have to live with retuning, like it or not. Digital and CW you can park yourself easily at one place and work that freq all day. SSB you really do need to run up and down the band more. In general the loop antenna is outstanding. I like mine. Have had little problems with it, other then the fact we have had much more wind then usual and mine is on a pole going up 20+ ft. The wind really banks it around and does do some de-tuning. Not much, but enough to bug me to a level where I might take it down and seeing if I can get some of the slop out of it. But I have been saying that for months and the problem has been so minor I just have not done it yet.

  • Harry N4HG:

    I have had the 1786 since the 1990’s! It is mounted on a short piece of TV mast to a roof tripod mount. Presently I live in a house in a ‘no outside antennas’ neighborhood and have the 1786 mounted horizontally in my attic. It works great. Especially on 15 and 10 meters. It does indeed have narrow bandwidth and has to be retuned after 10 or 15 kHz of frequency change but since I work mostly psk31 that isn’t any problem. The 1786 outperforms my G5RV (also attic mounted) on 15 and 10. An additional advantage is reduced noise. It is very quiet. It does work on 20 and 30 as well. I imagine its’ rather high price would offend many hams!

  • Mike VE3WDM:

    Good morning David, thanks for stopping by the blog and taking the time to comment. The antenna restrictive locations are now becoming more and more common. In my old home I was able to use the attic to my advantage. I used with great success the DXEE antenna. I had it in a Z config. Having said that I am glad to hear this review of the MFJ product has helped as well. Have a great what is left of the weekend!

  • Mike VE3WDM:

    Good morning Harry, I agree this antenna is idea for the digi modes and for sure the band width issue would not be a problem. I am a CW op (some digi) so the SSB is not an issue for this antenna. Thanks for the comment and I am sure the readers will find some additional answers from your comment.

  • Mike VE3WDM:

    Hello Harry (N4HG) I was surprised and pleased to read that the loop out preformed the G5RV and certain bands! Also one of the advantages that I missed in my post and you pointed out and that is how quite the antenna is on the bands. Lastly I agree it is a high priced antenna.

  • Jerry KK4GMU:

    If you ask a question about MFJ or any other loop antenna on forum sites like eHam or others, even if you include a painfully detailed description of your antenna-averse location, 9 out of 10 comments will try to talk you into something else.

    There are a number of reasons for this.

    1. They really don’t understand your conditions or circumstances.
    2. They didn’t fully read your opening post.
    3. They believe you are willing to spend weeks or months experimenting with and building antennas when all you want to do is get on the air.
    4. They assume you have a lot more interest or experience in building antennas than you do.
    5. They lack good information about what a well-designed loops can do.
    6. They don’t understand your goals and interests in ham radio and assume they are the same as theirs.
    7. They don’t realize that I already understand the challenges of loop antennas.
    8. Many urge “build your own.” Nope, not for an old guy who might run out of time before the first prototype is completed.

    I’m sure there are even more reasons for unhelpful responses. Yes, I understand most try to be sincerely helpful.

    I do appreciate the opinions of Mike and others, like Dave Casler, who have hands on and years of experience with loops versus just parroting the rumors they have heard or expression about choosing the wrong antenna (which happened to be a loop) for their broadcasting objectives.

    I am focused on the MFJ line of mag loops over the others like Chameleon and Alpha for several reasons:

    1. I want remote tuning. I like MFJ’s system. Others like Alpha are just beginning to provide that as an option – but increases their price point.
    2. I want to be able to transmit at my radio’s limit of 100 watts understanding the relatively low efficiency of mag loops. Most below $700 don’t allow for more than 20 to 30 watts. MFJ provides a cushion at 150 watts max.
    3. My deployment would be ONLY at my base station. Others are designed primarily for portable/field operation.
    4. I want it to remain outdoors. The MFJs (except the Box Fan 1780) are designed to be outside. True, even the Box Fan model could be covered to allow some protection.

    Of course I would love the fully automatic tuning of the Ciro Mazzoni Automatic Magnetic Loop Antennas for $2,500 – over three times the price of the best MFJ. Umm, no.

    And then we hear the MFJ horror stories concerning quality control. There are quite a number of eHam reviews among others. True, most who receive a new MFJ loop report a loose nut, or misaligned screws, or a need to tighten the set screw on the the capacitor shaft, or a need to realign a couple of air capacitor fins. But the GREAT majority of these reviewers also claim that they are very satisfied with the performance of their antenna after their “no brainer” repairs are made.

    So, here is my “no hands on” opinion of the three models of MFJ transmit mag loop antennas:

    MFJ-1789 (Box Fan): ~$400. 10 to 30 meters. One foot smaller loop diameter than the 1786 and 1788. I “suspect” this would make the tuning at 30 meters about as touchy as tuning 40 meters on the 1788. The case is some form of press board – not good in high humidity or outdoors in the rain. The remote tuner is more rudimentary than the ones on the 1786 and 1788. There is no SWR meter, although you can use your own between the radio and the remote tuner, or between the remote tuner and the antenna IF IT IS BATTERY OPERATED or does not share a common power source with the remote tuner.

    MFJ-1786: ~$650. 10 to 30 meters. Same loop diameter as the 1788. Same remote tuner, with SWR meter, as the 1788. The capacitor is a little smaller than the one in the 1788 due to no required tuning at 40 meters. Can be used outside like the 1788. This model may be the “sweet spot” among the three models. Some prefer the 1788 over this one because 40 meters is very popular for the most popular digital modes. There is much less activity on 30 and below. But it is also true that activity at 30 or below is likely to increase over the next several years for two reason: We’re heading into the solar maximum when propagation potential between 10 and 30 meters is improving, and modes like JS8 using JS8call are becoming more popular and are used on all bands.

    MFJ-1788: ~$710. 15 to 40 meters. Loses 10 to 12 meters but gains 40. Very touchy tuning at 40. Not much of an issue for narrow bandwidth digital. Will be something to think about for frequency roamers. For me, I have to consider how much I want to use 40 meters compared to 10 and 15 meters. Might I want to hook this up to my CB radio on 11 meters in a SHTF situation? How much would I really use 40 meters if it’s reported tuning is so finicky? Otherwise it is much the same as the 1786.

    So, there you have my assessment. Look me up to exchange ideas and opinions.


  • Mike Ve9KK:

    Good morning Jerry, it has been very nice emailing you and going over the MFJ loop and the time I have had with it. Very good points made in your above comment and I hope you get others as well who have owned a loop to give you some info and pointers on the loop.

  • Dave K8RDG/4:

    I vacation in a high-rise condo and my antenna options are severely limited so I chose the MFJ-1788 loop antenna. I purchased mine second-hand at about half the cost of a new one and have been using it for the last few years. I use it on my 3rd floor balcony (at night to avoid scrutiny/complaints from the condo association) with about 15 feet of RG-8X coax using a Comet CTC-50M window feed-through, and an additional 10 feet of RG-8X with a MFJ-915 RF Line Isolator inside connected to the MFJ controller. The antenna is somewhat heavy, but its small foot print makes it relatively easy to put up and take down, and doesn’t take up much space on the small balcony. I use 6′ of PVC pipe as a mast, strapped to the railing with Velcro straps. I primarily operate FT8 & FT4 at 25 watts which makes the 1788 ideal, since there is no frequency spread to tune. I did have to adjust the shape of the smaller loop inside the MFJ-1788 to improve my SWR. (Made it more circular than oval shaped.) I can now tune 40, 30, and 20 meters to less than 1.5:1 (20M is a flat 1.0:1); and 17 and 15 meters to less than 2.0:1. And, I’ve found that once I’ve fine tuned the controller to the lowest SWR, there is still room to further fine tune to bring the radio’s displayed SWR down to nearly match the controller’s display. I’ve also found that I cannot tune/use the antenna vertically. I have to use it horizontally to achieve low SWR, and I can’t use it inside, I have to use it outside. (At heights over 20 feet, the antenna is recommended to be used horizontally anyway.) The antenna takes some patience and getting used-to, but I’ve found that it works pretty well. One must remember that like many “multi-band” antennas, the 1788 is a “compromise” antenna and will likely not achieve a perfect SWR on all bands to begin with. While admittedly QSOs are quite challenging for me, especially on 40M, I have been able to digitally work as far as New Zealand, Australia, South Africa, Reunion Island, Lebanon, and much of western Europe and central Europe from my southeast Florida QTH depending on propagation. The MFJ-1788 has been a good choice for my restricted space situation.

  • Good afternoon Dave thanks for the comment and taking the time to read the post. You seem to have a great handle on the MFJ loop and its setup. I used the tripod that MFJ sells (not sure if they still do) to hold the loop and I covered it with a patio furniture cover. To the condo cops it looked like covered furniture and it never bothered the SWR at all. Using it for the digi mode is great as you said you don’t have to keep returning the loop. It’s always nice to read when all things radio seem to be working out.

  • Jerry KK4GMU:

    Hi again, Mike. This is Jerry from sunny to overcast Ocala, FL.
    I finally bit the bullet and ordered the MFJ-1786 from DX Engineering. 6 to 8 weeks till arrival. I got sidetracked from ham for a year after waiting for HRO’s delivery for 4 months while they had my credit card charged. The antenna never came in so I requested and received a refund. At least DX doesn’t charge you when the item is ordered like HRO does.

    I plan to integrate that antenna with my RSPdx/SDR UNO/Connect for some panadapter action with my IC-7100. I’ll be using the MFJ-1708B SDR as the protection switch along with a Noolectric LNA tempered by a switchable attenuator to help with the high insertion loss. I’m hoping to have both HF and VHF/UHF operate with the panadapter app. Wish me luck to not make magic smoke.

  • Mike VE9KK:

    Good morning Jerry and very nice to hear from you, I have always had good luck with DX Engineering every time I have dealt with them. When I order from the U.S I only deal with them. The MFJ 1708B I have heard some very good reports about it and how well it works. It is a wise idea to have one as its is cheap insurance so things won’t go bad. I hope the antenna does not take long to come in and do email me once you get it and let me know how its going with it.
    73 nice chatting,

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